Egypt plant installs first zero liquid discharge system
As environmental regulations mount in the industrial sector, water-starved regions, such as the Middle East, Northern Africa and Asia, have been particularly impacted in recent years. Some countries have implemented water discharge regulations that require zero-liquid discharge (ZLD). China’s power and coal-to-chemicals sectors are good examples of industries affected by these regulations. Additionally, in some regions of India industrial manufacturers with wastewater discharge to river systems are required to adopt ZLD technology.
Today’s strict discharge requirements demand cost-effective, energy-efficient, and reliable wastewater treatment solutions to purify and recycle virtually all wastewater produced, resulting in no harmful effluent discharged back into the environment. To achieve this, ZLD systems employ advanced wastewater treatment technologies.
Egypt’s First ZLD Plant
As Egypt instituted new environmental regulations prohibiting wastewater discharge in 2004, the Egyptian Ethylene and Derivatives Co. (ETHYDCO), the largest polyethylene (PE) production facility in Egypt, was determined to implement ZLD technology to meet compliance.
The initial design phase review estimated that the finished ETHYDCO plant would consume 2,600 cu meters per hour and needed to optimize the water consumption through conservation and recycling, reducing it by nearly 70% at 700 cu meters per hour. Thus, to maximize the lifecycle of incoming water from the River Nile and preserve freshwater resources, ETHYDCO decided to build Egypt’s first ZLD water treatment facility designed to recycle wastewater, allowing it to be continuously used in the production line.
A Pretreatment Solution
In order to produce water pure enough to meet ZLD standards, pretreatment is required before going through the ZLD process because high-efficiency reverse-osmosis systems call for highly filtered water that is free of solids and has low turbidity. ETHYDCO needed to identify a reliable filtration system capable of successfully handling its inconsistent water quality. It also has high total suspended solids (TSS) peaks; it is a composite mix of treated effluent and water from the River Nile. The complexity of the quality of the feed water varies throughout the year, resulting in seven different cases for the feed water based on varying TSS, feed turbidity and other feed water characteristics—further complicating matters.
Following an evaluation phase to determine the most suitable technology, Pall Water’s Aria FLEX membrane filtration system was selected to perform the pretreatment step for ETHYDCO’s ZLD system. The system offers strong membranes that can be designed with controls to allow operation at different feed scenarios.
The pretreatment solution is based on six trains with a total filtration area of 22,800 sq meters. Hydraulically, the system is capable of flow of more than 1,500 cu meters per hour, but to accommodate the various scenarios, it is designed to generate 1,041 to 1,093 cu meters per hour of filtered water to meet the plant’s massive capacity.
From Concept to Reality
From infancy, the ZLD system at the facility has met or exceeded expectations.
“I first conceptualized this plant in 2004 and worked with the ENPPI, ETHYDCO, Pall Water and Aquatech teams to turn this concept into a ZLD process solution,” said Hossam El-Fahmy, engineer and general manager for utilities and offsite for ETHYDCO. “More than a decade later, we are extremely pleased with the strength and reliability of the system which has helped us meet environmental regulations and gain global recognition.”
Following production, the system treats all of the ETHYDCO facility’s collected wastewater, purifying the water in the pretreatment phase ensuring that treated water is at a high enough quality to be used again in the PE production process. Despite the inconsistent water chemistry and difficulties associated with the feedwater, the strength of membranes are capable of running constantly at high recovery levels—ranging from 91% to 93%—at 100% production. Well-suited for the challenges of the feedwater, the reliability of the pretreatment system has proven crucial for operating at full capacity despite spikes in TSS, which at times can reach 177 parts per million, and varying feed conditions.
With the pretreatment system and the complete ZLD plant operational, ETHYDCO was able to meet all of the requisite norms of ZLD established by the Egyptian government to minimize water consumption and protect the country’s only life-giving aquifer, the River Nile.
With the successful completion of this project, ETHYDCO became the pioneer in ZLD and the model for industries in Egypt and across other Gulf Cooperation Council countries. It also is the first ethylene plant globally to achieve this accomplishment. As a result, this achievement has made ETHYDCO 100% environmentally friendly with no liquid waste released into the environment and thus a recipient of the 2016 Global Water Awards.